Narrow angle glaucoma (or angle closure glaucoma) is a special type of glaucoma, commonly seen in patients who are far-sighted. Patients with far-sighted eyes tend to have shorter eyes (front-to-back), and so the space inside the eye is physically smaller. As the natural lens inside the eye grows in size, it begins to crowd out the other structures within this smaller eye. One of these structures is the anterior chamber angle.
This anterior chamber angle of the eye is equivalent to the drain of a sink. When this structure is crowded, the liquid nutrients within the eye cannot drain away as easily, leading to a potential build-up of eye pressure. When the pressure is high enough to cause optic nerve damage (the optic nerve connects the eye to the brain), it is called narrow angle glaucoma or angle closure glaucoma.
More commonly, patients have angles which are at high risk for angle closure, but the optic nerve has not yet been damaged. This condition is referred to as anatomically narrow angles.